In a prior application, U.S. Ser. No. 210,082 filed Nov. 27, 1980 of Rokach et al., there is disclosed a class of 7 & 8 substituted-dibenzo[b,f]thiepin-3-carboxylic acid as well as the corresponding 5-oxides & 5,5-dioxides. This application discloses, further that certain of these compounds i.e. 7 & 8-fluoro-dibenzo[b,f]thiepin-3-carboxylic-5-oxides exist as racemic mixtures and are resolved into the respective enantiomeric pairs, one enantiomer of which has unusually high activity as a specific antagonist of contractile prostaglandins. Such enantiomers are therefore especially useful in the treatment of asthma, diarrhea, dysmenorrhea, pulmonary hypertension and threatened abortion. The production of such compounds involve fairly complicated syntheses and in order to produce final resolved isomer it is necessary to separate the "active" isomer from the "inactive isomer" with resultant lowered yield of product.